What situations call for the use of a slide master?

What will be an ideal response?

There may be times when you want to make a design change to all the slides in your presentation, such as changing the alignment or font size of text, or adding a logo to every slide. Instead of making the change on each slide, you can change the slide master. A slide master contains the layouts, design elements, and other formatting for a presentation. Every slide you create is based on a slide master. A slide master has a number of supporting layouts, or arrangements of slide placeholders, such as a Title slide layout, which has placeholders for a presentation title and subtitle, or a Title and Content layout, which has placeholders for a slide title and for slide content. You can customize a slide master, or any supporting layout, and save it for future use.